Mf-tdma frequency hopping

ABSTRACT

Systems, methods, and devices are described for scheduling and mapping upstream communications in a satellite communications system. The disclosure includes various channelization and frequency hopping techniques. A gateway is described to perform novel allocation of time slots on upstream frequency channels to allow frequency hopping. A subscriber terminal may perform frequency hopping according to the allocation, and the range may be limited to the transition range of a digitally controlled oscillator unit at the subscriber terminal. A gateway is described to allocate time slots on different upstream frequency channels in a prioritized manner. Subscriber terminals may receive the allocation, and then control the assignment of their upstream traffic to the time slots.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a Continuation of International Application No.PCT/US2007/079541, filed Sep. 26, 2007, entitled “Upstream ResourceAllocation for Satellite Communications”, and claims the benefit thereofunder 35 U.S.C. 120, which claims the benefit under 35 U.S.C. 119(e) ofU.S. Provisional Patent Application No. 60/827,999, filed Oct. 3, 2006,entitled “Upstream MF-TDMA Frequency Hopping” and U.S. ProvisionalPatent Application No. 60/827,994, filed Oct. 3, 2006, entitled“Upstream Resource Optimization”. This application is related to thefollowing U.S. patent application: U.S. patent application Ser. No.______, Attorney Docket No. 026258-002810US, filed concurrentlyherewith, entitled “Upstream Resource Optimization”. This applicationhereby incorporates by reference herein the content of theaforementioned applications in their entirety and for all purposes.

This application expressly incorporates by reference each of thefollowing patent applications in their entirety for all purposes:

PCT Application Serial No. PCT/US2007/079577, filed on Sep. 26, 2007,entitled “Improved Spot Beam Satellite Ground Systems” (Attorney DocketNo. 017018-009510PC);PCT Application Serial No. PCT/US2007/079561, filed on Sep. 26, 2007,entitled “Multi-Service Provider Subscriber Authentication” (AttorneyDocket No. 017018-007710PC);PCT Application Serial No. PCT/US2007/079565, filed on Sep. 26, 2007,entitled “Large Packet Concatenation In Satellite Communication System”(Attorney Docket No. 017018-008200PC);PCT Application Serial No. PCT/US2007/079569, filed on Sep. 26, 2007,entitled “Upfront Delayed Concatenation In Satellite CommunicationSystem” (Attorney Docket No. 017018-010510PC);PCT Application Serial No. PCT/US2007/079571, filed on Sep. 26, 2007,entitled “Map-Trigger Dump Of Packets In Satellite Communication System”(Attorney Docket No. 017018-010610PC);PCT Application Serial No. PCT/US2007/079563, filed on Sep. 26, 2007,entitled “Web/Bulk Transfer Preallocation Of Upstream Resources In ASatellite Communication System” (Attorney Docket No. 017018-010710PC);PCT Application Serial No. PCT/US2007/079567, filed on Sep. 26, 2007,entitled “Improved Spot Beam Satellite Systems” (Attorney Docket No.017018-008010PC);PCT Application Serial No. PCT/US2007/079523, filed on Sep. 26, 2007,entitled “Packet Reformatting For Downstream Links” (Attorney Docket No.026258-002700PC); andPCT Application Serial No. PCT/US2007/079541, filed on Sep. 26, 2007,entitled “Upstream Resource Allocation For Satellite Communications”(Attorney Docket No. No. 026258-002800PC).

BACKGROUND OF THE INVENTION

Consumer broadband satellite services are gaining traction in NorthAmerica with the start-up of star network services using Ka bandsatellites. While such first generation satellite systems may providemulti-gigabit per second (Gbps) per satellite overall capacity, thedesign of such systems inherently limits the number of customers thatmay be adequately served. Moreover, the fact that the capacity is splitacross numerous coverage areas further limits the bandwidth to eachsubscriber.

While existing designs have certain capacity limitations, the demand forsuch broadband services continues to grow. The past few years have seenstrong advances in communications and processing technology. Thisunderlying technology, in conjunction with selected novel upstreamscheduling techniques, may be utilized for satellite communicationssystems and components configured to address this demand.

BRIEF SUMMARY OF THE INVENTION

Systems, methods, and devices are described for scheduling and mappingupstream communications in a satellite communications system.Embodiments of the invention include various channelization andfrequency hopping techniques.

In one set of embodiments, a novel allocation of resources may beperformed for upstream frequency channels to allow frequency hopping.This allocation may be performed by a gateway device. In one embodiment,a determination is made that a traffic load on a first one of a numberof adjacent frequency channels exceeds a first threshold capacity. Asecond one of the frequency channels is selected. The selection is basedin part because an identified subscriber terminal transmitting on thefirst channel is configured with a digitally controlled oscillator unitable to transition between the first frequency channel and the secondfrequency channel during a transition period. Other factors that may beused in the selection of the second frequency channel are described, aswell.

Time slots are allocated to the subscriber terminal in the first andsecond frequency channels to allow frequency hopping between the firstfrequency channel and the second frequency channel for respective timeslot allocations. A subscriber terminal may perform frequency hoppingaccording to the allocation.

In another set of embodiments, time slots may be allocated on differentupstream frequency channels in a prioritized manner. This allocation mayalso be performed by a gateway device. In one embodiment, data isreceived from each of a number of subscriber terminals signalingrequests for upstream satellite transmission capacity for a time period.Some of the requested capacity is identified with transmissionspecifications limiting latency and packet spacing variance, thelimitations exceeding a threshold level. This identified capacity isclassified as prioritized traffic.

Time slots are allocated first to the prioritized traffic, andsubsequently to the remaining requests. The combined allocation for atime period is generated for each of the subscriber terminals, thecombined allocation made up of a generalized block of time slots for thetime period to be used as determined by respective subscriber terminals.Subscriber terminals may receive the allocation, and then control theassignment of their upstream traffic to the time slots based on theirown priority determinations.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the presentinvention may be realized by reference to the following drawings. In theappended figures, similar components or features may have the samereference label. Further, various components of the same type may bedistinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If only the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

FIG. 1 is a block diagram of a satellite communications systemconfigured according to various embodiments of the invention.

FIG. 2 is a block diagram of a ground system of gateways configuredaccording to various embodiments of the invention.

FIG. 3 is a block diagram of a satellite configured according to variousembodiments of the invention.

FIG. 4 is a block diagram of a gateway device configured according tovarious embodiments of the invention.

FIG. 5 is a block diagram illustrating a channelization format accordingto various embodiments of the invention.

FIG. 6 is a block diagram of a subscriber terminal device configuredaccording to various embodiments of the invention.

FIG. 7 is a block diagram of a frame formatted according to variousembodiments of the invention.

FIG. 8 is a block diagram of a modified digital video broadcast formataccording to various embodiments of the invention.

FIG. 9 is a channel diagram of a downstream channel diagram according tovarious embodiments of the invention.

FIGS. 10A-10C are diagrams of various channel and sub-channel structuresformatted according to embodiments of the invention.

FIGS. 11A and 11B are block diagrams illustrating alternativechanelization strictures according to various embodiments of theinvention.

FIG. 12A is a flow diagram illustrating the allocation of time slotsacross different frequency channels according to various embodiments ofthe invention.

FIG. 12B is a flow diagram illustrating frequency hopping acrossdifferent carrier frequencies according to various embodiments of theinvention.

FIG. 13 is a block diagram of a gateway device configured according tovarious embodiments of the invention.

FIGS. 14A-14B are block diagrams illustrating an upstream channelallocation according to various embodiments of the invention.

FIG. 15A is a block diagram of a subscriber terminal device configuredaccording to various embodiments of the invention.

FIG. 15B is block diagram illustrating an upstream channel assignmentaccording to various embodiments of the invention.

FIG. 16A is a flow diagram illustrating the allocation of time slots forprioritized traffic according to various embodiments of the invention.

FIG. 16B is a flow diagram illustrating the assignment of traffic acrosstime slot allocations according to various embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Systems, methods, and devices are described for scheduling upstreamsatellite communications. Various mapping, channelization, and frequencyhopping techniques are described for upstream satellite signals. Thedescription herein provides example embodiments only, and is notintended to limit the scope, applicability, or configuration of theinvention. Rather, the description of the embodiments will provide thoseskilled in the art with an enabling description for implementingembodiments of the invention. Various changes may be made in thefunction and arrangement of elements without departing from the spiritand scope of the invention.

Thus, various embodiments may omit, substitute, or add variousprocedures or components as appropriate. For instance, it should beappreciated that in alternative embodiments, the methods may beperformed in an order different than that described, and that varioussteps may be added, omitted, or combined. Also, features described withrespect to certain embodiments may be combined in various otherembodiments. Different aspects and elements of the embodiments may becombined in a similar manner.

It should also be appreciated that the following systems, methods, andsoftware may individually or collectively be components of a largersystem, wherein other procedures may take precedence over or otherwisemodify their application. Also, a number of steps may be requiredbefore, after, or concurrently with the following embodiments.

Referring first to FIG. 1, a block diagram illustrates an examplesatellite communications system 100 configured according to variousembodiments of the invention. While a satellite communications system isused to illustrate various aspects of the invention, it is worth notingthat certain principles set forth herein are applicable to a number ofother wireless systems, as well. The satellite communications system 100includes a network 120, such as the Internet, interfaced with a gateway115 that is configured to communicate with one or more subscriberterminals 130, via a satellite 105.

The network 120 may be any type of network and can include, for example,the Internet, an IP network, an intranet, a wide-area network (WAN), alocal-area network (LAN), a virtual private network (VPN), the PublicSwitched Telephone Network (PSTN), or any other type of networksupporting data communication between any devices described herein. Anetwork 120 may include both wired and wireless connections, includingoptical links. Many other examples are possible and apparent to thoseskilled in the art in light of this disclosure. The network may connectthe gateway 115 with other gateways (not pictured), which are also incommunication with the satellite 105, and which may share information onlink conditions and other network metrics.

The gateway 115 provides an interface between the network 120 and thesubscriber terminal 130. The gateway 115 may be configured to receivedata and information directed to one or more subscriber terminals 130,and format the data and information for delivery downstream to therespective subscriber terminals 130 via the satellite 105. Similarly,the gateway 115 may be configured to receive upstream signals 140 fromthe satellite 105 (e.g., log-in information, resource requests, or otherdata from one or more subscriber terminals 130). The upstream signalsmay be directed to the gateway 115 or another destination in the network120, and can format the received signals for transmission through thenetwork 120.

A device (not shown) connected to the network 120 may, therefore,communicate with one or more subscriber terminals 130 through thegateway 115. Data and information, for example, IP datagrams, may besent from a device in the network 120 to the gateway 115. The gateway115 may format a frame in accordance with a physical layer definitionfor transmission to the satellite 105 via a downstream link 135. Thenovel scheduling and mapping messages described herein may betransmitted downstream by the gateway, setting forth scheduling on theupstream links. A variety of physical layer transmission modulation andcoding techniques may be used with certain embodiments of the invention,including those defined with the DVB-S2 and WiMAX standards, or variousmodifications thereof.

In a number of embodiments, the gateway 115 utilizes Adaptive Coding andModulation (“ACM”) in conjunction with one or more of the downstreamtechniques described herein to direct messages to the individualterminals. The gateway 115 may use a broadcast signal, with a modulationand coding (modcode) format adapted to the link conditions of theterminal 130 or set of terminals 130 to which the packet is directed(e.g., to account for the variable service link 150 conditions from thesatellite 105 to each respective terminal 130). Both scheduling messagesand other data may be sent utilizing ACM.

The gateway 115 may use an antenna 110 to transmit the signal to thesatellite 105. In one embodiment, the antenna 110 is a parabolicreflector with high directivity in the direction of the satellite andlow directivity in other directions. The downstream signals 135, 150 mayinclude, for example, one (or more) single carrier signals. Each singlecarrier signal may be divided in time (e.g., using TDMA or other timedivision multiplexing techniques) into a number of sub-channels, whereinsubsets of the subscriber terminals are assigned to each sub-channel.The sub-channels may be the same size, or different sizes, and a rangeof options will be addressed below. In some embodiments, otherchannelization schemes may be integrated with or used in place oftime-divided sub-channels, such as Frequency Division Multiple Access(FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), CodeDivision Multiple Access (CDMA), or any number of hybrid or otherschemes known in the art.

In one embodiment, a geostationary satellite 105 is configured toreceive the signals from the location of antenna 110 and within thefrequency band and specific polarization transmitted. The satellite 105may, for example, use a reflector antenna, lens antenna, array antenna,active antenna, or other mechanism known in the art for reception and/ortransmission of signals. The satellite 105 may process the signalsreceived from the gateway 115 and transmit the signal from the gateway115 to one or more subscriber terminals 130. In one embodiment, thesatellite 105 operates in a multi-beam mode, transmitting a number ofnarrow beams, each directed at a different region of the earth, allowingfor frequency re-use. With such a multibeam satellite 105, there may beany number of different signal switching configurations on thesatellite, allowing signals from a single gateway 115 to be switchedbetween different spot beams. In one embodiment, the satellite 105 maybe configured as a “bent pipe” satellite, wherein the satellite mayfrequency-convert the received carrier signals before retransmittingthese signals to their destination, but otherwise perform little or noother processing on the contents of the signals. A variety of physicallayer transmission modulation and coding techniques may be used by thesatellite 105 in accordance with certain embodiments of the invention,including those defined with the DVB-S2 and WiMAX standards. For otherembodiments, a number of configurations are possible (e.g., using LEOsatellites, or using a mesh network instead of a star network), asevident to those skilled in the art.

The service signals transmitted from the satellite 105 may be receivedby one or more subscriber terminals 130, via the respective subscriberantenna 125. In one embodiment, the antenna 125 and subscriber terminal130 together make up a very small aperture terminal (VSAT). In otherembodiments, a variety of other types of antennas 125 may be used at thesubscriber terminal 130 to receive the signal from the satellite 105.Each of the subscriber terminals 130 may be a single user terminal or,alternatively, be a hub or router (not pictured) that is coupled withmultiple user terminals. Each subscriber terminal 130 may be connectedto consumer premises equipment (CPE) 160 (e.g., computers, local areanetworks, Internet appliances, wireless networks, etc.).

In one embodiment, a Multi-Frequency Time-Division Multiple Access(MF-TDMA) scheme is used for upstream links 140, 145, allowing efficientstreaming of traffic while maintaining flexibility in allocatingcapacity among each of the subscriber terminals 130. In variousembodiments, time slots on a frequency channel or set of frequencychannels are allocated for use to one or more subscriber terminals 130(for exclusive use, or use on a contention basis). A Time-DivisionMultiple Access (TDMA) scheme may be employed in each frequency channel.In such a scheme, each frequency channel may be divided into severaltimeslots that can be assigned to a connection (i.e., a subscriberterminal 130). The allocation may be fixed, or may be performed in amore dynamic fashion. In some embodiments, packets with certain qualityof service levels (e.g., real-time application with spacingrequirements) may receive priority allocations. In other embodiments,one or more of the upstream links 140, 145 may be configured with otherschemes, such as other TDMA, FDMA, OFDMA, CDMA, or any number of hybridor other schemes known in the art.

A subscriber terminal 130, using the upstream links, may transmit to thegateway 115 current or future bandwidth needs or requests, requests forapplications or services, information related to signal quality, etc. Asubscriber terminal 130 may also transmit data and information to anetwork 120 destination via the satellite 105 and gateway 115. Asubscriber terminal 130 may transmit the signals according to a varietyof physical layer transmission modulation and coding techniques. Invarious embodiments, the physical layer techniques may be the same foreach of the links 135, 140, 145, 150, or may be different. The gateway115 may use the resource request information to allocate time slots andfrequency channels on upstream links to particular subscriber terminals130. The gateway 115 may, in some embodiments, allocate sets offrequency channels to subscriber terminals 130 for upstreamcommunication based on the downstream sub-channel identifier associatedwith each respective subscriber terminal 130. The gateway 115 may alsouse the signal quality information to implement Adaptive Coding andModulation (ACM), adjusting the modcode formats to each terminal or setof terminals based on their link conditions.

In one embodiment, a gateway 115 includes a Satellite Modem TerminationSystem (SMTS), which is based at least in part on the Data-Over-CableService Interface Standard (DOCSIS). The SMTS in this embodimentincludes a bank of modulators and demodulators for processing signals tobe transmitted to or signals received from subscriber terminals 130. TheSMTS in the gateway 115 performs the real-time scheduling of the signaltraffic through the satellite 105, and provides the interfaces for theconnection to the network 120. In other embodiments, the schedulingoperations may be performed by other components or devices employingother standards.

In this embodiment, the subscriber terminals 130 use portions ofDOCSIS-based modem circuitry, as well. Therefore, DOCSIS-based resourcemanagement, protocols, and schedulers may be used by the SMTS forefficient provisioning of messages. DOCSIS-based components may bemodified, in various embodiments, to be adapted for use therein. Thus,certain embodiments may utilize certain parts of the DOCSISspecifications, while customizing others.

While a satellite communications system 100 applicable to variousembodiments of the invention is broadly set forth above, a particularembodiment of such a system 100 will now be described. In thisparticular example, approximately 2 gigahertz (GHz) of bandwidth is tobe used, comprising four 500 megahertz (MHz) bands of contiguousspectrum. Employment of dual-circular polarization results in usablefrequency comprising eight 500 MHz non-overlapping bands with 4 GHz oftotal usable bandwidth. This particular embodiment employs a multi-beamsatellite 105 with physical separation between the gateways 115 andsubscriber spot beams, and configured to permit reuse of the frequencyon the various links 135, 140, 145, 150. A single Traveling Wave TubeAmplifier (TWTA) may be used for each service link spot beam on thedownstream downlink, and each TWTA is operated at full saturation formaximum efficiency. A single wideband carrier signal, for example usingone of the 500 MHz bands of frequency in its entirety, fills the entirebandwidth of the TWTA, thus allowing a reduced number of space hardwareelements. Spotbeam size and TWTA power may be optimized to achievemaximum flux density on the earth's surface of −118 decibel-watts permeter squared per megahertz (dbW/m²/MHz).

Referring next to FIG. 2, an embodiment of a ground system 200 ofgateways 115 is shown in block diagram form. One embodiment may havefifteen active gateways 115 (and possibly spares) to generate sixtyservice spot beams, for example. The ground system 200 includes a numberof gateways 115 respectively connected with antennas 110. The gateways115 are also each connected to a network 120.

In one embodiment, a gateway 115 (e.g., gateway 115 of FIG. 1) mayupconvert and amplify a baseband signal (including data received fromthe network 120 or another gateway, and formatted according to variousembodiments of the invention) for transmission through the downstreamlink 135 via the antenna 110 to a particular subscriber terminal 130.Each gateway 115 may also downconvert the upstream links 140, andperform other processing as explained below (perhaps for forwardingthrough the network 120). Each gateway 115 may process signals to allowthe subscriber terminals 130 to log-in, and request and receiveinformation, and may schedule bandwidth. Additionally, a gateway 115 mayprovide configuration information and receive status from the subscriberterminals 130. Any requested or otherwise received information may beforwarded through the network.

Referring next to FIG. 3, an embodiment of a satellite 105 is shown inblock diagram form. The satellite 105 in this embodiment communicateswith fifteen gateways 115 and a number of subscriber terminals 130 usingsixty feeder and service spot beams. Other embodiments could use more orfewer gateways/spot beams. There may be any number of subscriberterminals 130 divided by geography between the service link spot beams.Buss power 315 is supplied using a power source such as chemical fuel,nuclear fuel, and/or solar energy. A satellite controller 320 is used tomaintain altitude and otherwise control the satellite 105. Softwareupdates to the satellite 105 can be uploaded from the gateway 115 andperformed by the satellite controller 320.

Information passes in two directions through the satellite 105. Adownstream translator 310 receives information from the fifteen gateways115 (e.g., formatted according to embodiments of the invention) forrelay to subscriber terminals 130 using sixty service spot beams. Anupstream translator 305 receives information from the subscriberterminals 130 occupying the sixty spot beam areas and relays thatinformation (e.g., log-in or signal quality information) to the fifteengateways 115. This embodiment of the satellite can switch carrierfrequencies in the downstream or upstream translators 310, 305 in a“bent-pipe” configuration, but other embodiments could do basebandswitching between the various forward and return channels. Thefrequencies and polarization for each spot beam may be programmable orpreconfigured.

I. Frequency Hopping: In another set of embodiments, systems, devices,and methods are described for the allocation and use of upstreamfrequency channels for frequency hopping. A variety of transmissiontechniques may be used for the upstream service links 145 and feederlinks 140 from the subscriber terminals 130 of the system 100 of FIG. 1.For example, the DVB-S or DVB-S2 standards may be used in a manner knownin the art. More specifically, a multi frequency-time division multipleaccess (MF-TDMA) technique may be used, such as the MF-TDMA scheme setforth in the Digital Video Broadcasting-Return Channel Satellite(DVB-RCS) standard. Either a fixed-slot or dynamic slot MF-TDMA systemmay be used. Alternatively, these or other standards may be modified inaccordance with one or more of the principles described below. Forexample, the DVB-RCS standard and other transmission techniquesutilizing MF-TDMA may be modified to provide for dynamic frequencyhopping in accordance with certain range limitation parameters.

Consider an MF-TDMA scheme in which a subscriber terminal 130 transmitssignals upstream to a gateway 115 via a satellite 105 using one of a setof carrier frequencies. The frequency range available for transmissionis divided up into a series of frequency channels, and the subscriberterminal 130 may change its carrier frequency to transmit on thedifferent channels. The bandwidth for each frequency channel may befixed or variable, and the channel size may be the same or differentbandwidths. The bandwidth of a given channel may vary dynamically withtime. Also, it is worth noting that while certain frequency ranges maybe allocated to specific terminals 130, other bands may be available forupstream use on a contention basis. Also, certain control or otherupstream signals may be transmitted on bandwidth available according toother transmission schemes. Within a given frequency channel, asubscriber terminal 130 may be given certain time slots fortransmission.

In one embodiment, the gateway 115 schedules the channel frequency andtime allocations for the subscriber terminals (e.g., with MAP messages),and transmits this control information downstream to subscriberterminals 130. The gateway may receive noise, interference, and otherinformation about the channels from subscriber terminals 130, thesatellite 105, other gateways 115-n, or other sources, and use thisinformation in identifying channel widths, and allocating channels andtime to subscriber terminals 130.

Referring next to FIG. 4, an embodiment of a gateway 115-b is shown inblock diagram form. This may be the gateway 115 of FIG. 1, and variousaspects of FIG. 1 will be used in describing the functionality of thegateway 115-b. The gateway 115-b may be configured to allocate timeslots on different upstream frequency channels to given subscriberterminal 130, and this allocation scheme may in one embodiment beemployed to allow increased packing efficiency for the upstream links140, 145.

In one embodiment, the gateway 115-b includes a receiving unit 405, amonitoring unit 410, a scheduling unit 415, and a transmitting unit 420,each of which may be in communication with each other directly orindirectly. In some embodiments, a device may include only a subset ofthese units, or may include additional units. The units of the device115-b may, individually or collectively, be implemented with one or moreApplication Specific Integrated Circuits (ASICs) adapted to perform someor all of the applicable functions in hardware. Alternatively, thefunctions may be performed by one or more other processing units (orcores), on one or more integrated circuits. In other embodiments, othertypes of integrated circuits may be used (e.g., Structured/PlatformASICs, Field Programmable Gate Arrays (FPGAs), and other Semi-CustomICs), which may be programmed in any manner known in the art. Thefunctions of each unit may also be implemented, in whole or in part,with instructions embodied in a memory, formatted to be executed by oneor more general or application-specific processors.

The receiving unit 405 may be configured to receive a variety ofinformation from the subscriber terminals 130 (via the satellite 105).This information may, for example, include log-in information, signalquality measurements, and service and bandwidth requests. Thisinformation may be transmitted from the subscriber terminals 130 to thegateway 115 via the upstream links 140, 145. The upstream links 140, 145may be made up of a number of adjacent frequency channels allocated forupstream satellite communications, wherein time slots on differentchannels are allocated to particular subscriber terminals 130.Alternatively, information may be received from one or more devices onthe network 120 that compile information passed from the subscriberterminals 130 or other sources. The receiving unit 405 may also receivea set of data (e.g., from the network 120) to be transmitted via thesatellite 105 and destined for one or more subscriber terminals 130.

The monitoring unit 410 of the gateway 115-b may be configured tomonitor a traffic load on each of the upstream frequency channels (e.g.,a set of adjacent frequency channels) for the upstream links 140, 145.The monitoring unit 410 may then determine that the traffic load on afirst frequency channel of the frequency channels exceeds a thresholdcapacity level. This determination may be made for an estimated oractual traffic load, and the traffic load may be a current or futureload. The threshold may in alternative embodiments be a fixed or dynamicpercentage of capacity (e.g., the dynamic threshold could vary withoverall traffic, and thus there might be a higher threshold when thetraffic is heavier).

When the determination is made, the scheduling unit 415, incommunication with the monitoring unit 410, is configured to identify asubscriber terminal transmitting upstream on the first frequencychannel. The scheduling unit 415 may select a second frequency channel(e.g., an adjacent or nearby frequency channel). The second frequencychannel may be selected because it has available capacity and becausethe subscriber terminal 130 has a digitally controlled oscillator unitcapable of transitioning between the first frequency channel and thesecond frequency channel (e.g., within the available time interval).

The scheduling unit 415 may allocate a first series of future time slotsin the first frequency channel to the subscriber terminal 130, andallocate a second series of future time slots in the second frequencychannel to the subscriber terminal 130. The first and second series maybe mutually exclusive so as to allow the subscriber terminal to hopbetween the first frequency channel and the second frequency channel forrespective time slot allocations. A transmitting unit 420, incommunication with the scheduling unit 415, may be configured totransmit data including the first and second series of allocations tothe subscriber terminal 130.

The functionality and options for certain units will now be explored ingreater depth. The receiving unit 405 may receive data messages (e.g.,on the upstream links 140, 145) from a number of the subscriberterminals 130. Some of the subscriber terminals 130 may be transmittingon the first frequency channel. In one embodiment, the subscriberterminals 130 may request additional current or future upstreambandwidth, or send data attempting to initiate a range of otherservices. These messages may, in some embodiments, be piggybacked ondata transmissions. A number of mechanisms may be used for the requests,including a modified DOCSIS request or modified RSVP request, adaptedfor use in the system 100 according to the parameters included herein.The messages may include an indication of the rate and/or duration ofrequested transmission, along with the type of traffic involved in thetransmission. A single subscriber terminal 130 may request more than oneallocation for a given time period (e.g., sending multiple messages).Thus, different streams from a single subscriber terminal 130 mayreceive different allocations.

This traffic type information may be indicated in a variety of ways, asknown in the art. Various protocols also include “type” fields whichcharacterize the traffic. Alternatively, port numbers, IP addresses, andprotocol identifiers may be used to identify types of traffic. A numberof alternative options are available, as evident to those skilled in theart. In addition to the type indication, the packet may also includeadditional class of service (CoS)/quality of service (QoS) parameters.

The receiving unit 405 may also be configured to receive data from asubscriber terminal indicating the range in which the digitallycontrolled oscillator unit is capable of transitioning to (e.g., fromthe first frequency channel, or more generally). The data may includeinformation on the speed in which such transitions may be made. In stillother embodiments, determinations regarding bandwidth needs andtransition ranges may be made more independently by the gateway 115-b,relying on historic requirements or other estimation algorithms based onmonitored traffic composition.

The monitoring unit 410 may use any of the data received by thereceiving unit 405 (or may use other data) in the determination as towhether the traffic load on the first frequency channel exceeds thethreshold capacity (e.g., a current or future threshold capacity). Thereceived data may, therefore, trigger the traffic load on the firstfrequency channel to exceed the first threshold capacity, either basedon specific bandwidth requests or other bandwidth allocations. Thethreshold may be a set or variable percentage below the actual orestimated capacity, and the threshold may be varied depending on trafficconditions. In addition, an imbalanced load on certain frequencychannels may trigger a swapping or reallocation for subscriber terminals130 across frequency channels.

The scheduling unit 415 may include memory to store a table or otherdata structure allocating time slots on one (or more) frequency channelsto each subscriber terminal 130 (e.g., by associating data linkaddresses or other identifier(s) for each subscriber terminal 130 withcertain time slots). In addition, the table may include information foreach of the subscriber terminals 130 (or a set of terminals) indicatingtheir frequency hopping abilities (e.g., range, transition speed,settling time, etc.). These abilities may be stored, received from thenetwork 120, or transmitted by each subscriber terminal 130 based onreal-time assessments on current frequency channels.

The scheduling unit 415 may thereby determine frequency hopping rangefor each of the subscriber terminals 130. When the monitoring unit 410determines that a traffic load on a given frequency channel exceeds thethreshold, the frequency hopping abilities of the subscriber terminals130 may be used in determining which terminal 130 will have some futureallocation moved to another frequency channel.

For a given subscriber terminal 130, the scheduling unit 415 may beconfigured to initially identify one, two, or more frequency channels towhich the digitally controlled oscillator unit is capable oftransitioning to from the first frequency channel. In anotherembodiment, the set of channels identified for possible frequencyhopping may be limited to transitions which may be performed coherently,limited to certain adjacent ranges of frequency, limited to closestchannels with available capacity, etc.

In selecting the second frequency channel from the identified options, aparticular selection may be based in part because the second frequencychannel: 1) includes a time slot that can be transitioned to coherentlyfrom the first frequency channel, 2) is the closest channel from thefirst frequency channel, 3) is the closest channel with availablecapacity, 4) is the channel within a range (e.g., 2 MHz above or below acurrent channels), 5) is an available channel with more availablecapacity than other available channels, 6) has a lower transitionalsettling time than other available channels, 7) is a channel which mayhave better options for future digital transitioning, 8) meets anycombination of the above factors.

While the selection of a possible set of channels for frequency hoppingand the identification of a particular channel for frequency hopping aredescribed as separate steps, it is worth noting that the steps may becombined, as well. Thus, a subset of the factors cited above may beaccounted for according to various weightings, and a determination ofthe frequency hopping channel may be made based thereon.

Turning to FIG. 5, a diagram 500 illustrating a set of upstreamfrequency channels 505 is shown. In this embodiment, assume that agateway 115 of FIG. 1 has allocated a subscriber terminal 130 certaintime slots 510 on a given upstream channel 505-4. The gateway 115 maythen determine that the channel capacity is insufficient for the currentor future traffic (e.g., because the traffic load in the channel exceedsa threshold). For example, perhaps the subscriber terminal 130 requestsadditional upstream capacity, and the channel 505-4 is fully allocatedor is loaded above a certain threshold during the previously unallocatedtime slots 515. Alternatively, a competing subscriber terminal 130-n mayhave requested more upstream capacity during such time slots. A numberof other possibilities exist which would give rise to a dynamicfrequency hopping scenario, as evident to those skilled in the art.Thus, at the time slots 515 when the subscriber terminal 130 is nottransmitting on its existing channel, a frequency synthesizer at thesubscriber terminal 130 may be controlled to change the carrierfrequency to allow the terminal 130 to transmit on other channels(505-1-505-3, 505-5-505-m).

Various embodiments of the invention, described above, may narrow therange of channels available for frequency hopping. In one embodiment,the gateway 115 uses various criteria to identify a set of channels 520for dynamic frequency hopping, and then identifies one or more channelsof that set for allocating capacity to the subscriber terminal 130. Inone embodiment, the set of channels 520 identified for possiblefrequency hopping may be limited to those channels 520 that may betransitioned to digitally by the digitally controlled oscillator.

In accordance with the above description, movement from one carrier toanother is possible on a burst-by-burst basis in some embodiments. Asubscriber terminal 130 may be configured to frequency hop dynamically(i.e., without carrying traffic for any significant length of time).Frequency transition is made without requiring log off or disablementduring a frequency transition. Turning next to FIG. 6, a block diagram600 is shown illustrating certain components of a subscriber terminal130-a, such as the subscriber terminal 130 of FIG. 1, configured fordynamic upstream frequency hopping transmissions. The subscriberterminal 130-a in this embodiment includes a receiving unit 605, aprocessing unit 610, an RF frontend 615, and one or more modulator(s)625. The subscriber terminal 130-a in this embodiment may be incommunication with the gateway 115 described with reference to FIG. 1,2, or 4.

In some embodiments, a device may include only a subset of these units,or may include additional units. The units of the device 130-a may,individually or collectively, be implemented with one or moreApplication Specific Integrated Circuits (ASICs) adapted to perform someor all of the applicable functions in hardware. Alternatively, thefunctions may be performed by one or more other processing units (orcores), on one or more integrated circuits. In other embodiments, othertypes of integrated circuits may be used (e.g., Structured/PlatformASICs, Field Programmable Gate Arrays (FPGAs), and other Semi-CustomICs), which may be programmed in any manner known in the art. Thefunctions of each unit may also be implemented, in whole or in part,with instructions embodied in a memory, formatted to be executed by oneor more general or application-specific processors.

The one or more modulator(s) 625 of the subscriber terminal 130-b mayreceive data from customer premises equipment 160-b or other sources,and encode and modulate the data to produce a modulated signal. Themodulated signal is transmitted to an RF frontend 615, where it may beprocessed by any number of amplifiers and filters (not shown). Afrequency synthesizer 620 in the RF frontend 615 produces a carriersignal, and a mixer 630 in the RF frontend 615 mixes the carrier andmodulated signal to produce an upconverted signal. This signal may thenbe processed by any number of amplifiers and filters (not shown), tothereby produce a signal for transmission to a satellite 105 via anantenna 125-b.

The frequency synthesizer 620 may include an analog frequencysynthesizer unit 640 and a digitally controlled oscillator (DCO) unit635. The analog frequency synthesizer 640, such as an analog PLLfrequency synthesizer, may be able to produce a broader range offrequencies, but there may be issues related to settling time. A DCO 635may be capable of quickly synthesizing a very wide range of precisefrequency ratios, but may have less range than its analog counterpart. Afrequency change may be implanted in a DCO 635 by writing a value into aregister, the value associated with a sinewave sample stored in alook-up table. This waveform is sent to a digital-to-analog converter toproduce an analog waveform, to produce the desired frequency. This mayallow for faster frequency changes, which may be conducive to thefrequency hopping environment. While in this embodiment the frequencysynthesizer 620 includes an analog frequency synthesizer unit 640 andDCO unit 635, in other embodiments there may be a standalone analog ordigital frequency synthesizer, or there may be a combination in series.A control signal may be received by the frequency synthesizer from aprocessing unit 610 to control the frequency synthesizer 620. Mappingdata used to produce the control signal may be received from the gateway115 with a receiving unit 605 at the subscriber terminal 130-a, andpassed to the processing unit 610.

In one embodiment, the analog frequency synthesizer unit 640 isconfigured to tune an output signal to a frequency within a frequencyrange allocated for upstream satellite communications. For example, theanalog frequency synthesizer unit 640 may be configured to tune anoutput signal to a frequency in the center channel of a number ofadjacent channels that may be available for allocation to the subscriberterminal 130-a to transmit upstream signals. The DCO unit 635 may beconfigured to vary the output signal among a set of carrier frequencieswithin a portion (or all) of the frequency range, each carrier frequencyof the set corresponding to a channel. For example, the portion of thefrequency range may be the identified set of channels 520 in FIG. 5allocated for dynamic frequency hopping. The set of channels 520identified for possible frequency hopping may be limited to thosechannels 520 that may be transitioned to digitally by the DCO unit 635,or may be even further limited.

The receiving unit 605 may receive data (e.g., from gateway 115-b)mapping the wireless upstream signals to different ones of the set ofcarrier frequencies in a series of time slots. The determinationregarding carrier frequencies at the gateway 115-b may be limited tocarrier frequencies that may be transitioned to digitally by the DCOunit 635, or according to other criteria. The processing unit 610 may beconfigured to control the digitally controlled oscillator unit to causethe varied output signal to hop between carrier frequencies according tothe received mapping data from the gateway 115-b.

In one embodiment, the processing unit 610 determines the set of carrierfrequencies that the DCO unit 635 is capable of transitioning to duringan available transition time. The transition time may be set dynamicallyby the processing unit 610 or a gateway 115-b, or may be predetermined.The processing unit 610 may generate a set of data for transmission, theset of data identifying the carrier frequencies available for transitionand perhaps identifying transition times, as well. The processing unit610 may set or advise further limits on the carrier frequencies whichmay be transitioned to, based on a determination of settling time,whether a channel may be transitioned to coherently, whether a channelis within a specified range, etc. The processing unit 610 may alsoidentify or estimate current or future bandwidth requirements andassociated traffic types, and generate data for transmission includingthis information.

In certain embodiments, a sub-channelization format may be used fordownstream transmission, and the upstream channelization formatting maycorrespond to differing degrees with the downstream formatting. Tobetter illustrate the options, the downstream formatting will bedescribed first. After the description of downstream formats isconcluded, the discussion will return to the corresponding upstreamoptions.

A gateway 115 (e.g., the gateway of FIG. 1, 2, or 4) may encapsulatedata (e.g., scheduling or other data) to be transmitted via thesatellite 105 to a subscriber terminal 130 (e.g., the subscriberterminal of FIG. 1 or 6). FIG. 7 is a block diagram illustrating anexample frame format 700 that may be used for such downstreamtransmission. A physical layer header 705 includes a header identifier710 and signaling data 715. The header identifier 710 may be one of aset of unique identifiers, so that its known sequence may be readilyidentified. For example, the destination subscriber terminal 130 may useknown patterns (one or more valid header identifiers) to correlate witha received signal. Destination subscriber terminals 130 may also beconfigured to store different sets of header identifiers 710, and thusframes may be filtered based on header identifier 710.

The remainder of physical layer header 705, the signaling data 715,includes the modcode data and a sub-channel identifier. The modcode dataidentifies the modulation and coding (e.g., the particular codewordsizes, code rates, modulation schemes, and pilot insertions) for encodedand modulated payload data 720 that is appended to the physical layerheader 705. The physical layer header 705 (or parts thereof) may beprotected by very low code rates so that it may be reliably receivedduring poor SNR conditions. The encoded and modulated payload data 720,however, is in many embodiments adaptively coded on a per-terminal (orper-set of terminals) basis. By way of example, a subscriber terminal130 receiving a transmitted signal at a very low SNR may receive a framein which the encoded and modulated payload data 720 has been encoded ata very low code rate and at a very low order modulation. Conversely, aterminal 130 receiving a transmitted signal at a very high SNR mayreceive a frame in which the encoded and modulated payload data 720 hasbeen encoded at a very high code rate and at a very high ordermodulation.

In addition, the signaling data includes a sub-channel identifierconfigured to identify different frames as belonging to particularsub-channels. By utilizing sub-channel identifiers in a physical layerheader 705, receiving devices (e.g., the subscriber terminals 130) mayfilter packets based on the sub-channel identifier without demodulatingor decoding the payload data 720. Thus, the information to bedemodulated and decoded (e.g., payload data 720 directed to othersub-channels and other subscriber terminals 130) may be limited orotherwise filtered thereby (as will be discussed in more detail below).A given sub-channel may, therefore, be a fraction (e.g., ¼, ⅛, 1/16) ofthe downstream channel. A subscriber terminal 130 may be configured tofilter a frame, demodulating and decoding payload data 720 only if thesub-channel identifier in the signaling data 715 matches one or moresub-channels for the terminal.

Turning to FIG. 8, the framing format 800 for a frame of a modifiedDVB-S2 system is set forth to illustrate various aspects of theinvention. The DVB-S2 frame format may be modified and used in thefollowing manner to implement the frame format 700 described withreference to FIG. 7. It is worth noting that in other embodiments,DVB-S, DVB-S2, WiMax, or other standards may be used, and this modifiedDVB-S2 format is for purposes of example only.

In one embodiment, each frame is broadcast downstream to all subscriberterminals 130, but is only directed (e.g., using the sub-channelidentifier and addressing label) at a select subscriber terminal 130 (orsmall groups of terminals). For example, the waveform may be a singlecarrier waveform transmitted downstream from a gateway 115 to asubscriber terminal 130 in the system 100 of FIG. 1. As noted above,while the DVB-S2 system is used as an example, the principles specifiedherein are applicable to a range of systems.

The header identifier 710 of FIG. 7 may be implemented as the Start ofFrame (SOF) 855 of FIG. 8, and the signaling data 715 may be implementedas a modified Physical Layer Signaling code (PLSCODE) 860. The SOF 855is a known 26-symbol pattern. The PLSCODE is a 64-bit linear binarycode, which conveys seven bits of information. In total, the SOF 855 andPLSCODE 860 occupy 90 symbols. In one embodiment, the format for thePLSCODE 860 is modified from the DVB-S2 standard so that the seven bitscarried inform receivers about the modcode (4 bits) and providesub-channel identifier information (3 bits). In other embodiments, otherformats are possible, with signaling data 715 of different sizes andformats. The PLSCODE 860 may be protected by a very low rate code toensure that it can be read correctly even in very poor SNR conditions.

The baseband frame 820 of FIG. 8 is made up of a baseband header 805, adata field 810, and padding 815. Data in the data field may, forexample, include one or more stream encapsulation headers, each appendedto one or more IP packets. The data field 810 may include a number ofstream encapsulation headers, each with an address label (e.g., the datalink layer address or shortened identifier) indicating the terminal orterminals (within the sub-channel) to which the packet will be directed.Packets associated with the same modcodes will typically be transmittedin the same baseband frame 820, although they may be combined forpacking efficiency. The DVB-S2 specification provides that certainframes will be of fixed size regardless of the modcode used (i.e., anormal FEC frame is 64,800 bits, and a shortened FEC frame is 16,200bits), leading to frames with different time durations. However, in someembodiments, frame size may be varied according to the modcode selectedfor the frame, to thereby produce frames of uniform duration in time.

Interleaving and FEC encoding (e.g., BCH and LDCP) may then be performedon the baseband frame 820. This produces a FEC Frame 840, made up of anencoded baseband frame 825 with outer coding parity bits 830 and innercoding parity bits 835 appended. While, as noted above, the DVB-S2specification provides that the FEC frame 840 will be of fixed datasize, in other embodiments, the FEC frame 840 size may vary according tothe modcode selected for the frame, to thereby produce frames ofsubstantially uniform duration in time.

The FEC frame 840 is bit mapped to the applicable constellation (e.g.,QPSK, 8PSK, 16APSK, 32APSK) to produce a XFEC frame 845. The XFEC frame845 may be the payload data 720 of FIG. 7. A PL header 850 is added tothe XFEC frame 845, together forming the PL frame 865. The PL header 850(which may be the header 705 of FIG. 7) is formatted as described aboveand encoded. The PL frame 865 is then baseband shaped and quadraturemodulated, as well as amplified and upconverted to be transmitteddownstream.

In one embodiment, PL frames 865 (and, thus, each corresponding basebandframe 820 encapsulated therein) are mapped one-for-one for eachsub-channel. Thus, it will be worthwhile to introduce certain principlesrelated to sub-channel assignment and allocation. Consider that gateway115 has received and encapsulated data destined for a subscriberterminal 130. For purposes of discussion, a set of frames fortransmission to a particular subscriber terminal 130 receiving a firstsub-channel are designated (PLF1 _(a), PLF1 _(b), PLF1 _(c), . . . PLF1_(n)). Assume that there are eight sub-channels. In one embodiment, around-robin technique is used where a first frame (PLF1 _(a)) is mappedto the first sub-channel, a second frame (not destined for the terminal)is mapped to a second-sub channel, and so on up to an eighth frame foran eighth sub-channel. The second frame destined for the terminal (PLF1_(b)) is then mapped to the first sub-channel, and the round-robinformat proceeds (i.e., PLF1 _(c), . . . PLF1 _(n) are each mapped to thefirst sub-channel in succession after each round). In this embodiment,each sub-channel corresponds to a set of subscriber terminals 130.

A number of other techniques of mapping frames to sub-channels may beused as well. For example, instead of a round-robin format, thesub-channel identifiers may be appended without the recurring order(e.g., based on the bandwidth requirements, or QoS, of the terminals forthe sub-channel). Thus, allocation and assignment of sub-channels may bevaried dynamically (e.g., a given sub-channel identifier could be usedfor a number of consecutive frames, or the allocation to a givensub-channel may be greater that other sub-channels). A number of hybridschemes are possible as well, as is evident to those skilled in the art,and thus a variety of multiplexing techniques may be used at thegateway.

Referring next to FIG. 9, a forward channel diagram 900 illustrating thesub-channel structure is shown for an embodiment of the invention. Theillustrated channel 905 goes from a gateway antenna 110 to thesubscriber terminal antennas 125 in a service beam area 915. The forwardchannel 905 operates at approximately 500 Mbps in this embodiment suchthat a service beam area 915 receives that bandwidth, but in otherembodiments could be at or above 100 Mbps, 250 Mbps, 750 Mbps, 1 Gbps,or 1.5 Gbps. A single carrier is used for transporting the forwardchannel 905, but other embodiments could use multiple carriers. Thesubscriber terminal 130 for this embodiment tracks at full rate (e.g.,500 Mbps), but does not completely demodulate and decode at full rate.Full demodulation and decoding only occurs for assigned sub-channels 910in the forward channel 905.

In this embodiment, the forward channel 905 is shown as an arrowencapsulating n dashed arrows, which are the n sub-channels 910. Thesub-channels 910 may each be portions of the superframe. In oneembodiment, the duration in time of the superframe does not change, butthe size of the superframe varies in other embodiments. A recurringblock size for each frame of a sub-channel 910 may be the same, orframes may vary in number and size. Some embodiments do not usesuperframes, but simply have sub-channels that are addressed to sets ofsubscriber terminals 130.

Subscriber terminals 130 may be configured to be capable of processingdifferent amounts of the forward channel 905. Some embodiments of thesubscriber terminal 130 may be configured to process at 1/16 datarate, ⅛datarate, ¼ datarate, ½ datarate, full speed, or any other fraction ofthe full data rate. In some cases, the subscriber terminal 130 may beconfigured to be incapable of running beyond a specified fraction of thefull rate or artificially capped even though capable of faster speeds.

FIGS. 10A-10C illustrate various options for different embodiments ofthe channel 905. Referring first to FIG. 10A, an embodiment of adownstream channel 905-a is shown. This embodiment uses sub-channels 910of a uniform block size in each superframe 1005-a, and because of ACM,the duration in time of each sub-channel (and thus each frame) may vary.Thus, although the duration in time of each superframe will often varyin this embodiment, the number of frames and order of frames within eachsuperframe will be constant.

Referring next to FIG. 10B, an alternative embodiment of a downstreamchannel 905-b is shown. This embodiment uses sub-channels 910 of avaried block size in each superframe 1005-b, adapting block size inlight of the applicable modcode, to produce sub-channels (and frames) ofsubstantially uniform duration in time. Thus, the data size of eachsuperframe will likely vary in this embodiment, but the number of framesper superframe 1005-b and the order of sub-channels within eachsuperframe 1005-b will be constant. In other embodiments, a superframe1005 could be of constant duration in time, and the number of frames persuperframe 1005 and order of sub-channels within each superframe 1005could vary.

Referring next to FIG. 10C, an alternative embodiment of a downstreamchannel 905-c is shown. This embodiment uses sub-channels 910 of avaried block size, adapting block size in light of the applicablemodcode, to produce frames of substantially uniform duration in time.However, in this embodiment, there is no superframe, and the order ofsub-channels 910 may vary. In one embodiment, the sub-channels may be inany order. In other embodiments, the system could be set to have certaintime slots for selected sub-channels, or have individual sub-channelsnot repeat more often than a certain threshold (e.g., more than 1 in 2,or 1 in 3 frames).

Turning to FIG. 11A, a diagram 1100 illustrating a number of sets ofupstream frequency channels 1105 is shown. In this embodiment, assumethat a gateway 115 of FIG. 1 is transmitting eight downstreamsub-channels, such as the sub-channels 910 discussed with reference toFIGS. 9 and 10A-10C. In the illustrated embodiment, sets of adjacentfrequency channels 1105 (e.g., in an MF-TDMA system) are allocated forupstream communications based on the sub-channel identifier associatedwith the respective subscriber terminals 130. Thus, in one embodiment,each of the subscriber terminals 130 associated with a given sub-channelmay share a set of upstream frequency channels 1105 (e.g., set 1105-1,set 1105-2, etc.). Time slots 1110 may be allocated to each of thesubscriber terminals 130 for their use in assigning upstream traffic.

The range of a DCO (e.g., DCO 635 of FIG. 6) at a subscriber terminal130, and perhaps other factors discussed above, may limit the frequencyhopping for a subscriber terminal to a narrower range 520-b of upstreamchannels. Thus, the analog frequency synthesizer (e.g., analog frequencysynthesizer 640 of FIG. 6) at different subscriber terminals 130 may bedirected to locate the initial frequency at different locations within agiven set of upstream frequency channels 1105. In one embodiment, thismay allow better utilization of each set of upstream frequency channels1105 associated with a given sub-channel.

In other embodiments, the range of a DCO (e.g., DCO 635 of FIG. 6) at asubscriber terminal 130, and perhaps other factors discussed above, maylimit the frequency hopping to a range 520-a of upstream channels thatcovers the entire set of upstream channels 1105-1 for a sub-channel.Turning to FIG. 11B, a diagram 1150 is shown illustrating a number ofgroups of upstream frequency channels 1105-1-a to 1105-1-h, showing anexample composition of the set of upstream frequency channels 1105-1.Each group is for the use of the subscriber terminals associated withsub-channel one. In this embodiment, the groups may each be allocated tocertain subsets of subscriber terminals 130 based on addresses (e.g.,MAC addresses in a first range in Group A 1105-1-a, MAC addresses in asecond range in Group B 1105-1-b, etc.). Such groups may be set, forexample, based on ranges of a DCO or other factors set forth above.

It is worth noting it may be desirable to have upstream traffic acrosssub-channels be relatively equal to maximize packing efficiency.Therefore, subscriber terminals 130 associated with differentsub-channels may be swapped or changed to balance loads across sets ofupstream channels (e.g., sets 1105-1 to 1105-8) or groups (e.g., groups1105-1-a to 1105-1-h). Alternatively, widths of sets of channels (e.g.,of channels 1105-1 to 1105-8) may be modified to balance such loads.

Referring next to FIG. 12A, a flowchart is shown illustrating a method1200 for allocating time slots to allow frequency hopping on wirelessupstream signals. The method may be performed, for example, in whole orin part, by the gateway 115 described with reference to FIG. 1, 2, or 4.

At block 1205, a determination is made that a traffic load on a firstone of a number of adjacent frequency channels exceeds a first thresholdcapacity. At block 1210, a subscriber terminal transmitting upstream onthe first frequency channel is identified. The subscriber terminal maybe identified because it has requested additional capacity, or for otherreasons as well. At block 1215, a second one of the frequency channelsis selected at least in part because the identified subscriber terminalis configured with a digitally controlled oscillator unit configured totransition between the first frequency channel and the second frequencychannel.

In other embodiments, the second one of the frequency channels may beidentified and/or allocated based on any of the following: 1) whetherthe channel may be transitioned to digitally within the transitionaltime period; 2) whether the transition to the channel may be performedcoherently; 3) how close the channel is from the currently allocatedchannel; 4) whether the channel has capacity, and how much capacity isavailable; 5) whether the channels surrounding the channel havecapacity, and how much capacity is available; 6) what the settling timeis for the channel; and 7) options for future digital transitioning,etc. A number of these factors may be accorded different weights, and adetermination of the frequency hopping channels may be made basedthereon.

At block 1220, a first series of time slots is allocated to thesubscriber terminal in the first frequency channel. At block 1225, asecond series of time slots is allocated to the subscriber terminal inthe second frequency channel, the second series exclusive of the firstseries. The first and the second series are allocated to allow thesubscriber terminal to hop between the first frequency channel and thesecond frequency channel for respective time slot allocations.

Referring next to FIG. 12B, a flowchart is shown illustrating a method1250 of frequency hopping on wireless upstream signals. The method maybe performed, for example, in whole or in part, by the subscriberterminal described with reference to FIG. 1 or 6.

At block 1255, mapping data is received, including a mapping of timeslots to different ones of a set of carrier frequencies within a subsetof a frequency range allocated for upstream satellite signals. Thismapping, for example, may be the first and second set of time slotallocations performed in block 1220 and block 1225, then transmittedfrom a gateway to a terminal. Thus, in such an embodiment, the carrierfrequencies may each be associated with a frequency channel. At block1260, an output signal is tuned to a frequency within the subset of thefrequency range. At block 1265, the output signal is controlled to hopamong the different ones of the set of carrier frequencies according tothe received mapping data, the variance limited to a digitallycontrolled oscillator range to which the output signal is capable oftransitioning from the tuned frequency during transitional periods.

II. Prioritized Upstream Resource Allocation: In another set ofembodiments, systems, devices, and methods are described for prioritizedupstream resource allocation and traffic assignments. The followingembodiments may be implemented using a variety of transmissiontechniques for the upstream service links 145 and feeder links 140 fromthe subscriber terminals 130 of the system 100 of FIG. 1. For example,the DVB-S or DVB-S2 standards may be used in any manner known in theart. More specifically, a MF-TDMA technique may be used, such as theMF-TDMA scheme set forth in the DVB-RCS standard. Either a fixed-slot ordynamic slot MF-TDMA system may be used. Alternatively, these or otherstandards may be modified in accordance with one or more of theprinciples described below. For example, the DVB-RCS standard and otherupstream transmission techniques utilizing MF-TDMA may be modified toprovide the scheduling mechanisms described herein for upstream resourceoptimization.

Referring next to FIG. 13, an example embodiment is shown of a system1300 with a gateway 115-c in communication with a number of subscriberterminals 130. This may be the gateway 115 of FIG. 1, and variousaspects of FIG. 1 will be used in describing the functionality of thisgateway 115-c. The gateway 115-c may be configured to allocate timeslots on different upstream frequency channels in a prioritized manner.Subscriber terminals may receive the allocation, and control theassignment of their upstream traffic to the time slots.

In one embodiment, the gateway 115-c includes an upstream trafficclassification unit 1305, an upstream resource allocation unit 1310, anda transmitting unit 1315, each of which may be in communication witheach other directly or indirectly. In some embodiments, a device mayinclude only a subset of these units, or may include additional units.The units of the device 115-c may, individually or collectively, beimplemented with one or more Application Specific Integrated Circuits(ASICs) adapted to perform some or all of the applicable functions inhardware. Alternatively, the functions may be performed by one or moreother processing units (or cores), on one or more integrated circuits.In other embodiments, other types of integrated circuits may be used(e.g., Structured/Platform ASICs, Field Programmable Gate Arrays(FPGAs), and other Semi-Custom ICs), which may be programmed in anymanner known in the art. The functions of each unit may also beimplemented, in whole or in part, with instructions embodied in amemory, formatted to be executed by one or more general orapplication-specific processors. The units and functionality of thedevice 115-c may be integrated with the units and functionality of thedevice 115-b described with reference to FIG. 4 (e.g., the trafficclassification unit 1305 may be integrated with the receiving unit 405,and the upstream resource allocation unit 1310 may be integrated withthe monitoring unit 410 and/or the scheduling unit 415).

Consider, for purposes of example, an MF-TDMA scheme in which asubscriber terminal 130 transmits signals upstream to a gateway 115 viaa satellite 105 using one of a set of carrier frequencies. The frequencyrange available for transmission is divided up into a series offrequency channels, and the subscriber terminal 130 may change itscarrier frequency to transmit on the different channels. The bandwidthfor each frequency channel may be fixed or variable, and the channelsize may be the same or different bandwidths. The bandwidth of a givenchannel may vary dynamically with time. Also, it is worth noting thatwhile certain frequency ranges may be allocated for MF-TDMA use, otherbands may be available for upstream use on a contention basis. Forexample, upstream resource request messages from a subscriber terminalin DOCSIS environments may be made on a contention channel. Within agiven frequency channel, a subscriber terminal 130 may be given certaintime slots for transmission.

In order to allocate frequency channels and time slices in such anMF-TDMA environment, a gateway 115-c may allocate the available slots,and broadcast this control information downstream to subscriberterminals 130 (e.g., with modified DOCSIS MAP messages). In otherembodiments, different gateway 115 configurations or components mayperform some or all of this functionality. It is also worth noting thatwhile MAP messages are discussed, embodiments of the invention areapplicable in a number of different systems and non-MF-TDMAenvironments.

The traffic classification unit 1305 may be configured to receive avariety of information from the subscriber terminals 130 (via thesatellite 105). This information may, for example, include log-ininformation and signal quality measurements, in addition to service,bandwidth, and other resource requests. The resource request messagesfrom subscriber terminal 130 may, in some embodiments, be piggybacked ondata transmissions. Thus, resource request messages may be separatecontrol messages, or implied or interpreted messages from particularstreams. This information may be transmitted from the subscriberterminals 130 to the gateway 115 via the upstream links 140, 145. Theupstream links 140, 145 may be made up of a number of adjacent frequencychannels allocated for upstream satellite communications, wherein timeslots on different channels are allocated to particular subscriberterminals 130. Alternatively, information may be received from one ormore devices on the network 120 that compile information passed from thesubscriber terminals 130 or other sources.

A number of mechanisms may be used to signal capacity requests,including a modified DOCSIS request or modified RSVP request, adaptedfor use in the system 100 according to the parameters included herein.The messages may include an indication of the rate and/or duration ofrequested transmissions, along with the type of traffic involved in thetransmission. A single subscriber terminal 130 may request more than onestream (e.g., sending multiple messages). Thus, different streams from asingle subscriber terminal 130 may receive different allocations.

This traffic type information may be indicated in a variety of ways, asknown in the art. In one embodiment, the type of traffic is indicated bywhether the transport protocol is TCP or UDP. Various protocols alsoinclude “type” fields which characterize the traffic. Alternatively,port numbers, IP addresses, and protocols may be used to identify typesof traffic. A number of alternative options are available, as evident tothose skilled in the art. In addition to the type indication, the packetmay also include additional class of service (CoS)/quality of service(QoS) parameters. The time period(s) for allocating time slots for agiven set of requests may be set by various units of the gateway 115-c,or may be otherwise received.

The upstream traffic classification unit 1305 may, using the resourcerequest messages, identify and/or classify the traffic into categories.For example, in one embodiment, the requested allocations are classifiedas prioritized traffic or non-prioritized traffic. This identificationsand/or classifications may be based, in whole or in part, on adetermination that the transmission specifications limiting latency andpacket spacing variance for certain traffic exceed a threshold level.

The transmission specifications may be looked up based on traffic type,or may be specifically included in the request. These transmissionspecifications may include latency, jitter, rate, packet size, packetspacing, requested duration, and other requirements of the identifiedtraffic categories and/or types, in light of the satellite link atissue. Satellite links have intrinsic delay, including propagation delayon the uplink and downlink for the upstream request message, thepropagation delay on the uplink and downlink for the downstream responseallocation message, and the propagation delay on the uplink and downlinkfor the upstream transmission, in addition to processing time. Forinteractive services, therefore, reducing latency and jitter may be ofincreased importance.

As noted, the identification and/or classification may be based, inwhole or in part, on a determination that transmission specificationslimiting latency and packet spacing variance exceed a threshold level.Various interactive services, such as VoIP, conferencing, interactivemultimedia services, and so on, may be classified as prioritizedtraffic. The threshold for latency may be a set delay or latencythreshold, or may be implemented by identifying a maximum packet size.The threshold for the packet spacing variance may also be implemented asa jitter limit, or a substantially equidistant spacing requirementbetween each of a series of packets. It is also worth noting that theidentified traffic may be classified as prioritized traffic in a numberof different ways (e.g., using other methods and levels ofclassification).

Traditional web traffic, document transfers, software downloads, andcertain streaming services will in many instances not meet thethreshold. This traffic may remain without a classification, or may beassociated with intermediate levels of classification.

The capacity requests, transmission specifications, andidentifications/classifications for prioritized traffic are thenprocessed by the upstream resource allocation unit 1310. Assume that, inthis embodiment, traffic is classified as prioritized traffic ornon-prioritized traffic. The upstream resource allocation unit 1310first allocates resources to the prioritized traffic according to thetransmission specifications, identifying sets of time and frequencyslots for each stream. For circuit emulation voice traffic, for example,slot assignment may be directed at spreading voice packets across anumber of small bursts (e.g., each packet containing a 10 ms, or 20 ms,sample). Also, the packets may be regularly spaced in time (e.g., toallow for transmission of each packet as soon as possible after it isencapsulated, to minimize delay/latency).

In one embodiment, the upstream resource allocation unit 1310 identifiescertain frequency channels for prioritized traffic, and this allocationmay exclude non-prioritized traffic. In another embodiment, the upstreamresource allocation unit 1310 attempts to first identify and fillcertain frequency channels with prioritized traffic that has certainlike spacing requirements, and then allocates some of the remainingspaces in the channel to non-prioritized traffic.

Preference may be also given to keeping a subscriber terminal 130 on thesame channel or group of channels for all types of traffic. Inallocating non-prioritized traffic, the upstream resource allocationunit 1310 may, therefore, give preference to traffic of a firstsubscriber terminal 130 if the frequency channel(s) includes theprioritized traffic of the first subscriber terminal 130. The upstreamresource allocation unit 1310 may, in other embodiments, exclude othersubscriber terminals 130 not associated with prioritized traffic offrequency channel(s) allocated to that prioritized traffic. Preferencemay be given to keeping streams of a subscriber terminal 130 allocatedto adjacent channels, or certain ranges of channels, perhaps includingthe frequency hopping range considerations discussed above. Thisresource allocation may be characterized as adaptive mapping,dynamically selecting available frequency and time slots first forprioritized traffic. Predictions based on current traffic compositionand capacity levels may be used to implement predictive schedulingtechniques. Therefore, the upstream resource allocation unit 1310 mayalso specify a duration period extending outside the current allocationperiod to each latency-sensitive stream.

After allocating the time slots in the frequency channel(s) to theprioritized traffic, upstream resource allocation unit 1310 allocatessome or all of the remainder of the traffic on a capacity-availablebasis. Various queuing configurations may be utilized to give preferenceto streams with longer pending requests. Preference may also be grantedto traffic with certain QoS levels. By first dynamically allocating timeslots to the prioritized traffic, and then dynamically allocating theremainder, available upstream traffic may be more efficiently allocatedin some embodiments.

The upstream resource allocation unit 1310 then translates thesefrequency channel and time slot allocations into a frame compositionmessage for each subscriber terminal 130. This frame composition messageis a generalized block of time slots for the time period to be used asdetermined by (or under the control of) a subscriber terminal 130. Atransmitting unit 1315 then broadcasts the message downstream to therespective subscriber terminals 130. This frame composition messagecontains the channel and time allocations for a given allocation period.Each subscriber terminal may then use the frame composition message todetermine the channel and time slots for each of its stream requests.

While the above discussion assumes that traffic is classified asprioritized traffic or non-prioritized traffic, the classificationscheme may be parsed further. For example, with latency-sensitivetraffic, applications may be further classified as constant bit rateservices (e.g., certain voice applications, such as circuit emulationvoice), or variable bit rate services. Constant bit rate services may beassociated with services with relatively stable, consistent demand,whereas variable bit rate services are associated with uneven demand. Iflatency-sensitive packets are divided among constant and variable bitrate services, the allocation unit may be configured to allocatetime/frequency slots to the constant bit rate services first, then tothe variable bit rate services. Certain QoS parameters attributed tocertain streams may also dictate one or more streams be allocated beforeothers.

Turning to FIG. 14A, a diagram 1400 illustrating a set of upstreamfrequency channels 1405 is shown. Each upstream frequency channel 1405-1to 1405-m may be an upstream channel 505 as described for FIG. 5. Theset of upstream frequency channels may be a set (set 1105-1, set 1105-2,etc.) as described with reference to FIG. 11A. The embodimentillustrated in FIG. 14A is an example allocation of channel time slots.An upstream resource allocation unit 1310 of the gateway 115-c of FIG.13, for example, may be configured to allocate time slots to differentsubscriber terminal 130 streams over an allocation period 1425. Certainstream requests are identified as prioritized traffic, and other streamrequests are identified as non-prioritized traffic. Time slots forstreams are first allocated to the prioritized traffic: a stream from afirst subscriber terminal 130 is allocated time slots 1410-1 in a firstupstream channel 1405-2, a second stream from a second subscriberterminal 130 is allocated time slots 1410-2 in a different upstreamchannel 1405-4, and three additional streams from other subscriberterminals are allocated to time slots 1410-3, 1410-4, 1410-5 in a thirdupstream channel 1405-7. The upstream resource allocation unit 1310attempts to identify and fill frequency channel 1405-7 with prioritizedtraffic streams that have certain like spacing and/or size requirements(e.g., streams allocated to time slots 1410-3, 1410-4, 1410-5 have likespacing requirements). The upstream resource allocation unit 1310 thenmay allocate some of the remaining spaces in the channel tonon-prioritized traffic, if capacity permits.

With the allocation of the prioritized traffic completed, the remainingtraffic 1415 is allocated to the open time slots as illustrated by thediagram 1450 of FIG. 14B. Channels may be shared with thelatency-sensitive traffic in the unallocated time slots of the channels.Also, non-prioritized streams from the second subscriber terminal 130may be allocated open time slots 1415-2 within or outside the channel1405-4 carrying the prioritized traffic from that terminal 130. Theremay, but need not, be a requirement or preference that a channel 1405-4carrying the prioritized traffic from a subscriber terminal 130 alsocarry the non-prioritized traffic of the terminal 130. There may also bea requirement or preference that a channel 1405-6 adjacent to a channel1405-7 carrying prioritized streams from a subscriber terminal 130 alsocarry the non-prioritized streams of the terminal 130.

The allocation period will, in some embodiments, be contracted to lowerlatency at the cost of increased use of system resources. Also, theremay be different configurations for different allocation periods. Forexample, in one embodiment, an allocation period may be a longerduration, but control messages may be sent many times within the period.In another embodiment, the upstream resource allocation unit 1310 maymap and shape traffic by factoring previous channel time slotallocations into future allocation. A number of other alternatives areavailable, as well, as evident to those skilled in the art.

In yet another embodiment, rate control functionality may be included inthe upstream resource allocation unit 1310, as well. In one suchembodiment, the allocation requests attributed to prioritized trafficstreams are analyzed to determine whether there is or will becongestion. Then, control messages may be transmitted downstream fromgateway 115-c the to a subscriber terminal 130 to modify a codec in use,or increase the sample period (e.g., from 10 ms to 20 ms). Similarly,such a change may be implemented for certain audio/video conferencingand other latency-sensitive services, thereby proactively modifyingfuture requests for resource allocation.

In accordance with the above description, the allocation of time slotsfor a time period may be made up of a block of time slots allocated, butnot assigned, to particular streams. A subscriber terminal 130 may beconfigured to receive the allocation, and then assign its actual trafficdynamically. Turning next to FIG. 15, a block diagram 1500 is shownillustrating certain components of a subscriber terminal 130-b, whichmay be the subscriber terminal 130 of FIG. 1, configured to assigntraffic to time slot allocations in a prioritized manner. The subscriberterminal 130-b in this embodiment may be in communication with thegateway 115 described with reference to FIG. 1, 2, 4, or 13.

The subscriber terminal 130-b in this embodiment includes a resourcerequest unit 1505, an upstream mapping unit 1510, one or moremodulator(s) 1515, and a transmitting unit 1520. In some embodiments, adevice may include only a subset of these units, or may includeadditional units. The units of the device 130-b may, individually orcollectively, be implemented with one or more Application SpecificIntegrated Circuits (ASICs) adapted to perform some or all of theapplicable functions in hardware. Alternatively, the functions may beperformed by one or more other processing units (or cores), on one ormore integrated circuits. In other embodiments, other types ofintegrated circuits may be used (e.g., Structured/Platform ASICs, FieldProgrammable Gate Arrays (FPGAs), and other Semi-Custom ICs), which maybe programmed in any manner known in the art. The functions of each unitmay also be implemented, in whole or in part, with instructions embodiedin a memory, formatted to be executed by one or more general orapplication-specific processors.

The resource request unit 1505 of the subscriber terminal 130-b mayreceive data from customer premises equipment 160-c or other sources.Using this data, resource request unit 1505 generates capacity requestsfor each of a number of streams. The capacity requests may be any of theservice, bandwidth, and other resource requests received by the upstreamclassification unit 1305 of FIG. 13. As noted above, the capacityrequests may be associated with transmission specifications includinglimitations on latency and packet spacing variance. Such capacityrequests may be encoded and modulated by modulator 1515, and transmittedupstream by the transmitting unit to the gateway 115 via antenna 125-b.

In response to the capacity requests, the upstream mapping unit 1510 ofthe subscriber terminal 130-b may receive an allocation of time slotsfor a time period. The allocation may be a block of time slotsunassigned to particular streams, or may otherwise allow the subscriberterminal 130-b to determine or otherwise control traffic assignmentdynamically. The allocation may be the frame composition messageproduced by the upstream resource allocation unit 1310 transmitted tothe subscriber terminal 130-b.

The upstream mapping unit 1510 may then identify and classify at leastsome of the data traffic to be transmitted in the time period asprioritized subscriber terminal traffic. The classification may bebased, in whole or in part, on a determination as to whethertransmission specifications include limitations on latency and packetspacing variance that exceed a threshold level. This threshold level maybe the same, or different, than the threshold applied by an upstreamtraffic classification unit 1305 at a gateway 115-c transmitting theallocation. For example, if a subscriber terminal 130-b wants totransmit a greater amount of traffic than requested or allocated, thethreshold may be modified to shape traffic or better ensure that certainhigh priority traffic is transmitted.

The upstream mapping unit 1510 may then dynamically assign theprioritized subscriber terminal traffic to the allocation in a set oftime slots. This assignment may be made because the assigned slotsconform with the limitations on latency and/or packet spacing variance.The upstream mapping unit 1510 may assign a set of data traffic to theallocation in the first set of time slots without the resource requestunit 1505 first generating a capacity request for the first set of data.The upstream mapping unit 1510 may subsequently assign the data trafficnot classified as prioritized subscriber terminal traffic to the timeslots remaining in the allocation. In one embodiment, the time slotsremaining in the allocation do not conform to the limitations on latencyand/or packet spacing variance of the prioritized traffic.

The transmitting unit 1515 may transmit the traffic streams to betransmitted upstream (e.g., from CPE 160-c or elsewhere) according toassignments for the first and second set of time slots.

Turning to FIG. 15B, a diagram 1550 illustrates a set of upstreamfrequency channels 1405, allocated as described with reference to FIG.14A. Assume that subscriber terminal 130-b in FIG. 15A is allocated timeslots 1410-3 in upstream channel 1405-7, and times slots 1415-3 inupstream channel 1405-6. This allocation may be received by the upstreammapping unit 1510 of subscriber terminal 130-b. In one embodiment, theallocation is a block of time slots unassigned to particular streams,allowing the subscriber terminal 130-b to determine or otherwise controltraffic assignment dynamically. The allocation may be the framecomposition message produced by the upstream resource allocation unit1310 transmitted to the subscriber terminal 130-b.

The upstream mapping unit 1510 may then identify and classify at leastsome of the data traffic to be transmitted in a time period asprioritized subscriber terminal traffic. The classification may bebased, in whole or in part, on a determination as to whethertransmission specifications include limitations on latency and packetspacing variance that exceed a threshold level. This threshold level maybe the same, or different, than the threshold applied by an upstreamtraffic classification unit 1305 at the gateway 115-c transmitting theallocation. The upstream mapping unit 1510 may then dynamically assignthe prioritized subscriber terminal traffic 1555 to the allocation in aset of time slots 1410-3. This assignment may be made because theassigned slots conform with the limitations on latency and/or packetspacing variance. The upstream mapping unit 1510 may subsequently assignthe non-prioritized data traffic 1560 a first time slot 1415-3-aremaining in the allocation. With no additional traffic to transmit inthe period, the remaining time slot 1415-3-c may go unassigned 1565.

Referring next to FIG. 16A, a flowchart is shown illustrating a method1600 for allocating time slots to prioritized traffic on wirelessupstream signals. The method may be performed, for example, in whole orin part, by the gateway 115 described with reference to FIG. 1, 2, 4, or13.

At block 1605, data is received from each of a number of subscriberterminals signaling requests for upstream satellite transmissioncapacity for a time period. At block 1610, a subset of the requestedcapacity is identified with transmission specifications limiting latencyand packet spacing variance, the limitations exceeding a thresholdlevel. At block 1615, the identified subset is classified as prioritizedtraffic.

At block 1620, a first set of time slots in the time period is allocatedfor the prioritized traffic, the first set allocated according to thetransmission specifications. At block 1625, a second set of time slotsin the time period is subsequently allocated to the capacity requestsnot classified as prioritized traffic. At block 1630, a combinedallocation for the time period is generated for each of the subscriberterminals, the combined allocation comprised of a generalized block oftime slots for the time period to be used as determined by respectivesubscriber terminals.

Referring next to FIG. 16B, a flowchart is shown illustrating a method1650 of assigning traffic on wireless upstream signals. The method maybe performed, for example, in whole or in part, by the subscriberterminal 130 described with reference to FIG. 1, 6, or 15A.

At block 1655, capacity requests are transmitted for each of a number ofdifferent streams, wherein at least a subset of the capacity requestsare associated with transmission specifications including limitations onlatency and packet spacing variance. At block 1660, an allocation oftime slots for a time period is received in response to the capacityrequests, the allocation comprised of a block of time slots unassignedto particular streams. This allocation may be the generalized block oftime slots generated at block 1630 of FIG. 16A, transmitted from agateway 115 to a subscriber terminal 130.

At block 1665, a subset of data traffic to be transmitted in the timeperiod is identified as prioritized subscriber terminal traffic, theidentification based on a determination that the subset includeslimitations on latency and packet spacing variance that exceed athreshold level. At block 1670, the prioritized subscriber terminaltraffic is dynamically assigned to the allocation in a first set of timeslots. At block 1675, the data traffic not classified as prioritizedsubscriber terminal traffic is subsequently assigned to the allocationin a second set of time slots. At block 1680, the traffic is transmittedaccording to the assignments in the first set and the second set of timeslots.

It should be noted that the methods, systems and devices discussed aboveare intended merely to be examples. It must be stressed that variousembodiments may omit, substitute, or add various procedures orcomponents as appropriate. For instance, it should be appreciated that,in alternative embodiments, the methods may be performed in an orderdifferent from that described, and that various steps may be added,omitted or combined. Also, features described with respect to certainembodiments may be combined in various other embodiments. Differentaspects and elements of the embodiments may be combined in a similarmanner. Also, it should be emphasized that technology evolves and, thus,many of the elements are exemplary in nature and should not beinterpreted to limit the scope of the invention.

Specific details are given in the description to provide a thoroughunderstanding of the embodiments. However, it will be understood by oneof ordinary skill in the art that the embodiments may be practicedwithout these specific details. For example, well-known circuits,processes, algorithms, structures, and techniques have been shownwithout unnecessary detail in order to avoid obscuring the embodiments.

Also, it is noted that the embodiments may be described as a processwhich is depicted as a flow diagram or block diagram. Although each maydescribe the operations as a sequential process, many of the operationscan be performed in parallel or concurrently. In addition, the order ofthe operations may be rearranged. A process may have additional stepsnot included in the figure.

Moreover, as disclosed herein, the term “memory” or “memory unit” mayrepresent one or more devices for storing data, including read-onlymemory (ROM), random access memory (RAM), magnetic RAM, core memory,magnetic disk storage mediums, optical storage mediums, flash memorydevices, or other computer-readable mediums for storing information. Theterm “computer-readable medium” includes, but is not limited to,portable or fixed storage devices, optical storage devices, wirelesschannels, a sim card, other smart cards, and various other mediumscapable of storing, containing, or carrying instructions or data.

Furthermore, embodiments may be implemented by hardware, software,firmware, middleware, microcode, hardware description languages, or anycombination thereof. When implemented in software, firmware, middleware,or microcode, the program code or code segments to perform the necessarytasks may be stored in a computer-readable medium such as a storagemedium. Processors may perform the necessary tasks.

Having described several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theinvention. For example, the above elements may merely be a component ofa larger system, wherein other rules may take precedence over orotherwise modify the application of the invention. Also, a number ofsteps may be undertaken before, during, or after the above elements areconsidered. Accordingly, the above description should not be taken aslimiting the scope of the invention.

1. A device for generation of wireless upstream signals for satellitecommunications, the device comprising: an analog frequency synthesizerunit configured to tune an output signal to a frequency within afrequency range allocated for upstream satellite communications; adigitally controlled oscillator unit, coupled with the analog frequencysynthesizer unit, and configured to vary the output signal among a setof carrier frequencies within a subset of the frequency range; areceiving unit configured to receive data mapping the wireless upstreamsignals to different ones of the set of carrier frequencies in a seriesof time slots, the mapping limited to carrier frequencies within thesubset of the frequency range; and a processing unit, communicativelycoupled with the digitally controlled oscillator unit and the receivingunit, and configured to control the digitally controlled oscillator unitto cause the varied output signal to hop between carrier frequenciesaccording to the received data.
 2. The device of claim 1, wherein theprocessing unit is further configured to: determine the set of carrierfrequencies, the set comprising carrier frequencies to which thedigitally controlled oscillator unit is capable of transition during anavailable transition time.
 3. The device of claim 1, wherein theprocessing unit is further configured to: generate a set of data fortransmission, the set of data identifying carrier frequencies to whichthe digitally controlled oscillator unit is capable of transition duringa predetermined transition time.
 4. The device of claim 1, wherein theprocessing unit is further configured to: identify the different ones ofthe set of carrier frequencies based at least in part on a determinationof settling time for transitions between the different ones.
 5. Thedevice of claim 1, wherein the processing unit is further configured togenerate data for transmission identifying current bandwidthrequirements and associated traffic types for the device.
 6. The deviceof claim 1, wherein the processing unit is further configured togenerate data for transmission estimating future bandwidth requirementsand associated traffic types.
 7. The device of claim 1, wherein, thesubset of the frequency range is allocated for upstream satellitecommunication for a subset of a plurality of subscriber terminalstransmitting upstream in the frequency range, the subset of subscriberterminals associated with a selected sub-channel identifier of aplurality of sub-channel identifiers.
 8. The device of claim 1, wherein,each one of the set of carrier frequencies corresponds to a frequencychannel allocated for use in upstream satellite communications; and thefrequency channels comprise frequency channels in a multi-frequencytime-division multiple access system.
 9. A method of generating wirelessupstream signals for satellite communications, the method comprising:receiving data including a mapping of time slots to different ones of aset of carrier frequencies within a subset of a frequency rangeallocated for the wireless upstream signals; tuning an output signal toa frequency within the subset of the frequency range; and varying theoutput signal to hop among the different ones of the set of carrierfrequencies according to the received mapping data, the variance limitedto a digitally controlled oscillator range to which the output signal iscapable of transitioning from the tuned frequency during transitionalperiods.
 10. A device for allocating time slots on a plurality ofadjacent frequency channels for upstream satellite communications to aplurality of respective subscriber terminals, the device comprising: amonitoring unit configured to: monitor a traffic load on the pluralityof adjacent frequency channels; and determine that the traffic load on afirst frequency channel of the plurality of adjacent frequency channelsexceeds a first threshold capacity; a scheduling unit, communicativelycoupled with monitor unit, and configured to: identify a firstsubscriber terminal of the plurality of respective subscriber terminals,the first subscriber terminal transmitting upstream on the firstfrequency channel; select a second frequency channel of the plurality ofadjacent frequency channels, the second frequency channel selected basedat least in part because the first subscriber terminal is configuredwith a digitally controlled oscillator unit capable of transitioningbetween the first frequency channel and the second frequency channel;allocate a first series of future time slots in the first frequencychannel to the first subscriber terminal; and allocate a second seriesof future time slots in the second frequency channel to the firstsubscriber terminal, the second series exclusive of the first series andallocated so as to allow the first subscriber terminal to hop betweenthe first frequency channel and the second frequency channel forrespective time slot allocations; and a transmitting unit,communicatively coupled with the scheduling unit, and configured totransmit data directed at the first subscriber terminal, the datacomprising the first series and the second series.
 11. The device ofclaim 10, further comprising: a receiving unit, communicatively coupledwith the monitoring unit, and configured to receive data from theplurality of respective subscriber terminals each transmitting on thefirst frequency channel requesting future upstream bandwidth, whereinthe monitoring unit is further configured to use the received data inthe determination of whether the traffic load on the first frequencychannel exceeds the first threshold capacity, the traffic loadcomprising a future traffic load.
 12. The device of claim 10, furthercomprising: a receiving unit, communicatively coupled with themonitoring unit, and configured to receive data from the firstsubscriber terminal transmitting on the first frequency channel andrequesting additional upstream bandwidth, wherein the additionalupstream bandwidth causes the traffic load on the first frequencychannel to exceed the first threshold capacity.
 13. The device of claim10, further comprising: a receiving unit, communicatively coupled withthe monitoring unit, and configured to receive data from the firstsubscriber terminal identifying a subset of the plurality of adjacentfrequency channels, the identified subset comprising two or morefrequency channels the digitally controlled oscillator unit is capableof transitioning to from the first frequency channel.
 14. The device ofclaim 10, wherein the threshold capacity is less than a total capacityfor the first frequency channel.
 15. The device of claim 10, wherein thescheduling unit is configured to select the second frequency channelbased at least in part because the second frequency channel includes atime slot that can be transitioned to coherently from the firstfrequency channel.
 16. The device of claim 10, wherein the schedulingunit is configured to select the second frequency channel based at leastin part because the frequency channel is a closest channel from thefirst frequency channel.
 17. The device of claim 10, wherein thescheduling unit is configured to select the second frequency channelbased at least in part because the frequency channel is an availablechannel with more available capacity than other available channels. 18.The device of claim 10, wherein the scheduling unit is configured toselect the second frequency channel based at least in part on a settlingtime associated with transition between the first frequency channel andthe second frequency channel.
 19. The device of claim 10, wherein thescheduling unit is further configured to: identify a subset of theplurality of adjacent frequency channels, the subset comprising two ormore frequency channels the digitally controlled oscillator unit iscapable of transitioning to from the first frequency channel.
 20. Thedevice of claim 10, wherein the scheduling unit is further configuredto: assign a first subset of the plurality of adjacent frequencychannels for exclusive use among a first subset of the plurality ofrespective subscriber terminals; and assign a second subset of theplurality of adjacent frequency channels for exclusive use among asecond subset of the plurality of respective subscriber terminals. 21.The device of claim 20, wherein the transmitting unit is furtherconfigured to: transmit a first downstream packet with a firstsub-channel identifier in a physical layer header, the first sub-channelidentifier used to differentiate packets destined for the first subsetof the plurality of respective subscriber terminals; and transmit asecond downstream packet with a second sub-channel identifier in aphysical layer header, the second sub-channel identifier used todifferentiate packets destined for the second subset of the plurality ofrespective subscriber terminals
 22. The device of claim 20, wherein eachof the first subset of frequency channels is adjacent to at least oneother frequency channel of the first subset of frequency channels, andeach of the second subset of frequency channels is adjacent to at leastone other frequency channel of the second subset of frequency channels.23. A method of allocating time slots on a plurality of adjacentfrequency channels for upstream satellite communications, the methodcomprising: determining that a traffic load on a first frequency channelof the plurality of adjacent frequency channels exceeds a firstthreshold capacity; identifying a subscriber terminal transmittingupstream on the first frequency channel; selecting a second frequencychannel of the plurality of adjacent frequency channels, the secondfrequency channel selected based at least in part because the subscriberterminal is configured with a digitally controlled oscillator unitconfigured to transition between the first frequency channel and thesecond frequency channel; allocating a first series of time slots in thefirst frequency channel to the subscriber terminal; and allocating asecond series of time slots in the second frequency channel to thesubscriber terminal, the second series exclusive of the first series,wherein the first and the second series of time slots are allocated toallow the subscriber terminal to hop between the first frequency channeland the second frequency channel for respective time slot allocations.24. A system for allocating time slots in frequency channels forupstream satellite communications, the system comprising: a gatewaydevice configured to: monitor a traffic load on the plurality ofadjacent frequency channels; determine that the traffic load on a firstfrequency channel of the plurality of adjacent frequency channelsexceeds a first threshold capacity; and select a second frequencychannel of the plurality of adjacent frequency channels, the secondfrequency channel selected based at least in part because a subscriberterminal using the first frequency channel is configured with adigitally controlled oscillator unit to transition between the firstfrequency channel and the second frequency channel; allocate a firstseries of time slots in the first frequency channel to the subscriberterminal; allocate a second series of time slots in the second frequencychannel to the subscriber terminal, the second series exclusive of thefirst series and allocated so as to allow the subscriber terminal to hopbetween the first frequency channel and the second frequency channel forrespective time slot allocations; and transmit data including the firstseries and second series directed at the subscriber terminal via asatellite; the satellite, in wireless communication with the gatewaydevice and the subscriber terminal, and configured to receive thetransmitted data and retransmit the received data to the subscriberterminal; and the subscriber terminal configured to: receive theretransmitted data; and hop between the first frequency channel and thesecond frequency channel according to the received mapping data.
 25. Thesystem of claim 24, wherein the subscriber terminal is configured to:determine a set of carrier frequencies to which the digitally controlledoscillator unit is capable of transition, each carrier frequency of theset corresponding to a selected one of the adjacent frequency channels;and transmit data comprising the determined set of carrier frequenciesto the gateway device.